Problem: Solve for $y$ : $7 = y - 6$
Add $6$ to both sides: $ \begin{eqnarray} \\ \hphantom{7 {+ 6}} &\hphantom{=}& \hphantom{y} \\ 7 &=& y - 6 \\ \\ {+6} && {+6} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 7 {+ 6} &=& y \\ \end{eqnarray} $ Simplify. $ y = 13$